Medium to long chain alkyl aromatics are used to make high volume additives and surfactants. Examples of such compounds are alkyl aromatic sulfonates used in lubricant additives. Alkyl aromatic sulfonates are also used in surfactants such as detergents. Another potential use for alkyl aromatic sulfonates is in Enhanced Oil Recovery (EOR) chemicals where EOR chemical is used to increase the productivity of an oil field. Different chain lengths and branching of the alkyl chain of the alkyl aromatic are used depending on the application. The thermal and oxidative stability of alkyl aromatic based additives and surfactants is increasingly important and desirable in specific uses. In the area of lubricant additives the lubricants are being subjected to more severe conditions and longer drain intervals and the desire is to have lubricant compositions that are stable longer. In EOR chemicals it is highly desired to have surfactants that are stable for long periods of time at very extreme temperatures and pressures. An EOR chemical may have to be active for several years. Dealkylation of significant amounts of the alkylaromatic sulfonate can lead to loss of activity of the EOR chemical. Likewise dealkylation of an alkyl aromatic lubricant additive is counterproductive to the goal of increased miles between oil changes and to maintain performance.
A particular type of alkyl aromatic used to make oil additives are alkyl phenols used to make phenates. Phenates can be used in oil additives as sulfurized metal phenates. Phenate based oil additives and methods of making them are discussed in U.S. Pat. Nos. 3,178,368, 3,367,867, and 4,927,551 all of which are herein incorporated by reference in their entirety. Processes for making specific alkyl phenol isomers are disclosed in U.S. Pat. Nos. 4,532,368, 4,538,008, and 4,447,657 all which are incorporated herein by reference.
Methods for making alkylaromatic sulfonate surfactants and desired features of the alkyl groups are discussed in U.S. Pat. Nos. 6,602,840 and 6,566,319 which are herein incorporated by reference in their entirety.
Desired characteristics of, and methods of making alkyl aromatic sulfonates suitable for use as EOR chemicals are disclosed in U.S. Pat. Nos. 6,269,881 and 6,765,106 which are incorporated herein in their entirety.
In most alkylaromatic sulfonate processes the alkylaromatic is made by the alkylation of an aromatic such as benzene, toluene, phenol or xylenes, with a long chain monoolefin such as a Normal Alpha Olefin (NAO). NAOs are available in a number of specific chain lengths. In the conventional alkylation of an aromatic with an NAO the aromatic tends to attach to the 2 position of the olefin in higher than statistical proportions to form a methyl branched linear alkyl aromatic where a methyl or higher branch is attached to the carbon that is attached to the aromatic as shown below:

As mentioned above in some of the applications using alkyl aromatics and alkyl aromatic sulfonates high temperature conditions can be employed. Under high temperature, severe oxidative and or thermal conditions dealkylation of the alkyl group of the alkyl aromatic or alkyl aromatic sulfonate can occur. A secondary branched carbon center (secondary alkylate) can be a good leaving group under such severe conditions. A tertiary center (tertiary alkylate) provides even a better leaving group thus is even less stable. An alkyl aromatic having a primary center (primary alkylate) is more stable but as discussed above is not favored in conventional alkylation chemistry. Thus a method of making a more stable alkyl aromatic and alkyl aromatic sulfonate would be useful. The present invention provides such a method.